Electrospun Biodegradable Nanofibers Coated Homogenously by Cu Magnetron Sputtering Exhibit Fast Ion Release. Computational and Experimental Study

Abstract

Copper-coated nanofibrous materials are desirable for catalysis, electrochemistry, sensing, and biomedical use. The preparation of copper or copper-coated nanofibers can be pretty challenging, requiring many chemical steps that we eliminated in our robust approach, where for the first time, Cu was deposited by magnetron sputtering onto temperature-sensitive polymer nanofibers. For the first time, the large-scale modeling of PCL films irradiation by molecular dynamics simulation was performed and allowed to predict the ions penetration depth and tune the deposition conditions. The Cu-coated polycaprolactone (PCL) nanofibers were thoroughly characterized and tested as antibacterial agents for various Gram-positive and Gram-negative bacteria. Fast release of Cu2+ ions (concentration up to 3.4 µg/mL) led to significant suppression of E. coli and S. aureus colonies but was insufficient against S. typhimurium and Ps. aeruginosa. The effect of Cu layer oxidation upon contact with liquid media was investigated by X-ray photoelectron spectroscopy revealing that, after two hours, 55% of Cu atoms are in form of CuO or Cu(OH)2. The Cu-coated nanofibers will be great candidates for wound dressings thanks to an interesting synergistic effect: on the one hand, the rapid release of copper ions kills bacteria, while on the other hand, it stimulates the regeneration with the activation of immune cells. Indeed, copper ions are necessary for the bacteriostatic action of cells of the immune system. The reactive CO2/C2H4 plasma polymers deposited onto PCL-Cu nanofibers can be applied to grafting of viable proteins, peptides, or drugs, and it further explores the versatility of developed nanofibers for biomedical applications use.

Biodegradable Nanohybrid Materials as Candidates for Self-Sanitizing Filters Aimed at Protection from SARS-CoV-2 in Public Areas

“…The COOH plasma polymer layer almost entirely covered the PCL-Cu-COOH samples, as only 0.4 at.% of Cu was detected by XPS (Table 1). The composition of PCL-Cu-COOH was similar to the surface chemistry reported previously [32,37,39].…”

“…According to Reference [32], Cu 2+ released from PCL-Cu is about 80 µg/L/day (for incubation in the 50-mL volume), while in our study, the Ag ion release was ~15 µg/L/day. More intensive Ag + ion implantation was not possible due to the degradation of the nanofibrous structure at a high voltage.…”

“…The average values are shown in Figure 3. In the energy range under consideration, a power law dependence of the penetration depth on the atom's energy is obtained, described by the linear equation L = 9.0 × 10 −3 E in contrast to the power equation (L = 4.07 × 10 −2 E 0.7739 ) in Reference [32] for Cu penetration to PCL. During the penetration into the PCL, the metal atom can change the movement direction due to collisions with polymer atoms, the penetration angle of the silver atom is random and the average deviation angle for all simulations is 2.86 degrees, which are two times smaller in comparison with Cu atom [32] due to atomic weight difference.…”

“…All silver atoms were bonded to oxygen in Ag 2 O, as it can be concluded from the symmetrical shape of the Ag 3d 5/2 and Ag 3d 3/2 lines and the position of BE for Ag 3d 5/2 of 368.2 eV [38]. The Cu layers were deposited onto PCL nanofibers, and this process was thoroughly investigated elsewhere [32]. The C1s signal of the as-prepared PCL nanofibers (PCL-ref) can be fitted by the sum of four components, namely hydrocarbons CH x (BE = 285 eV), carbon neighbored to ester group C-C(O)O (BE = 285.5 eV), ether group C-O (BE = 286.4 eV) and ester group C(O)O (BE = 289.0 eV).…”

Hybrid Films Prepared from a Combination of Electrospinning and Casting for Offering a Dual-Phase Drug Release

“…When these polymers are transferred into nanofibers with a certain poorly water-soluble drug, the dissolution enhancement effects are greatly improved because of the unique properties of electrospun nanofibers, such as small diameters, high porosity, and the amorphous state of the loaded drug molecules [ 30 , 31 ]. Upon encountering water, the medicated nanofibers often are able to release the loaded drugs in a pulsatile manner, freeing the drug molecules all at once [ 32 , 33 ]. This drug controlled release profile is very useful for a series of diseases where fast therapeutic actions are required, e.g., fever, pain, depression, and heart disease [ 34 , 35 , 36 ].…”